Computer Science 1 Top Lectures Assignments Noticeboard Introduction

What and Why of Computer Programming

• What -

  A collection of instructions and commands that can be executed by a computer

• Why - automate and enhance various tasks -
  • Life-critical Applications
    • Hospital Patient Monitoring Systems
    • Airplane Guidance Systems
    • Nuclear Reactor Control Systems
  • Information Systems
    • Employee Payroll
    • Student Records
    • The World Wide Web
  • User Applications
    • Word Processors
    • Spreadsheets
    • Checkbooks
  • Computer Systems
    • Operating Systems
    • Networks
    • System Administration
  • Entertainment
    • Games
    • Televisions

Programming - The Recipe Analogy

• Recipes Are Similar to Programs

  Mom's Chicken Soup
   Ingredients:                   Preparation:
   -----------------------------------------------------------------------
   1 chicken quartered            1.  Boil a pot of water with salt.
   6 carrots                      2.  Cut each carrot in half
   2 parsnips                     3.  Place chicken, carrots, parsnips,
   2 celery sticks                    celery, and pepper in water.
   1/2 bunch of dill              4.  Soak dill and parsley in cold water
   1/2 bunch of parsley               and salt.
   1 tablespoon of salt           5.  After 45 minutes (about half hour
      and pepper as needed            before soup is done), place dill,
   1 parsley root                     parsley, parsley root in pot.
  

• Recipe Writing versus Recipe Running
• Notice, some concepts familiar programming also arise in cooking:
  • types - classes of things (e.g., spices, vegetables)
  • objects - instances of classes of things (e.g., salt and pepper, carrots, parsnips, parsley)
  • sequences - commands that occur in order (e.g., melt butter and then fry onions)
  • iteration - collection of commands executed until some event occurs (e.g., for each vegetable, wash and dice finely, until no more)
  • parallel - tasks that occur simultaneously (e.g., while meat is cooking, prepare vegetables)
  • parameterisation - arguments to a general procedure (e.g., beef, chicken)
  • different techniques - more efficient, flexible, easier, etc.
  • requirements, design, implement, test, debug, etc.